Image sensor and driving method thereof

ABSTRACT

An image sensor according to some example embodiments includes a pixel array unit including a plurality of transmission signal lines and a plurality of output signal lines, and a plurality of pixels connected to the plurality of transmission signal lines and the plurality of output signal lines. Each of the plurality of pixels includes a plurality of photoelectric conversion elements, which are configured to detect and photoelectrically convert incident light. The plurality of pixels include at least one autofocusing pixel and at least one normal pixel.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. application Ser.No. 15/461,929, filed on Mar. 17, 2017, which claims priority under 35U.S.C. § 119 to Korean Patent Application No. 10-2016-0111089, filed inthe Korean Intellectual Property Office on Aug. 30, 2016, the entirecontents of which are incorporated herein by reference.

BACKGROUND (a) Technical Field

The present disclosure relates to an image sensor and/or a drivingmethod thereof.

(b) Description of Related Art

An electronic device, such as a digital camera and a smart phone, havinga function of photographing an image may include an image sensor. Theimage sensor may include a charged coupled device (CCD) image sensor, acomplementary metal oxide semiconductor (CMOS) image sensor, and thelike as a semiconductor device for converting optical information intoan electric signal. Among them, the CMOS image sensor is mainly used.

The CMOS image sensor includes a photoelectric conversion element and aplurality of pixels including a plurality of transistors. A signalphotoelectrically converted by the photoelectric conversion element maybe processed and output by the plurality of transistors, and image datamay be generated based on a pixel signal output from the pixel. Eachpixel may photoelectrically convert light of a specific color or in aspecific wavelength range, and output a signal according to thephotoelectrically converted light.

An electronic device having a function of photographing an image mayhave an autofocusing control function using an image sensor in order tocontrol the focus. A phase difference detection method among variousautofocusing control methods may determine whether an image is focusedby dividing light incident to a pixel of a sensor into two or moreelements of light and comparing the two or more elements of light.According to a result of the determination of whether the image is infocus, the focus may be automatically controlled by moving aphotographing optical system included in an electronic device.

The above information disclosed in this Background section is only forenhancement of understanding of the background of inventive concepts.Therefore, it may contain information that does not qualify as prior artart.

SUMMARY

Inventive concepts relate to improving a sensitivity of an image sensorand/or further improving a resolution of an image sensor. Inventiveconcepts also relate to reducing a read time of a pixel signal in animage sensor having a phase difference detection function for anautofocusing control function, and obtain a high reading speed even inan image sensor having high resolution. Inventive concepts also relateto increasing sensitivity of phase difference detection and increasingprecision of an autofocusing control of objects with all of the colors.

In some example embodiments, an image sensor includes a pixel array unitincluding a plurality of pixels connected to a plurality of transmissionsignal lines and a plurality of output signal lines. Each of theplurality of pixels includes a plurality of photoelectric conversionelements that are configured to detect and photoelectrically convertincident light. The plurality of pixels includes at least oneautofocusing pixel and at least one normal pixel.

In some example embodiments, a method of driving an image sensor isprovided. The image sensor includes a plurality of pixels. The pluralityof pixies include at least one autofocusing pixel and at least onenormal pixel. Each of the plurality of pixels include a plurality ofphotoelectric conversion elements. The method includes reading outautofocusing pixel signals, which are photoelectrically converted by theplurality of photoelectric conversion elements included in one of the atleast one autofocusing pixel, respectively, at different timings, andreading out normal pixel signals, which are photoelectrically convertedby the plurality of photoelectric conversion elements included in one ofthe at last one normal pixel, respectively , simultaneously.

In some example embodiments, an image sensor includes a pixel arrayunit. The pixel array unit includes a plurality of pixels connected to aplurality of transmission signal lines and a plurality of output signallines. Each of the plurality of pixels includes a plurality ofphotoelectric conversion elements that are configured to detect andphotoelectrically convert incident light. Four pixels adjacent to eachother in a quadrangular shape among the plurality of pixels define onepixel unit. The pixel unit includes at least one autofocusing pixel andat least one normal pixel.

According to some example embodiments, an image sensor includes aplurality of pixel units, a plurality of transmission signal lines, aplurality of output signal lines, and a signal processing unit connectedto the plurality of pixel units through the plurality of transmissionsignal lines and the plurality of output signal lines. Each of theplurality of pixel units includes a plurality of pixels that eachinclude a plurality of photoelectric conversion elements. Each of theplurality of pixel units includes an autofocusing pixel and a normalpixel among the plurality of pixels. The signal processing unit isconfigured to determine corresponding to an external object based onactiving two of the plurality of photoelectric conversion elements inthe autofocusing pixel differently during a time interval.

According to some example embodiments, it is possible to increasesensitivity of an image sensor and decrease crosstalk, thereby furtherincreasing resolution of the image sensor. Further, it is possible todecrease a read time of a pixel signal in an image sensor having a phasedifference detection function for an autofocusing control function,thereby obtaining a high reading speed even in an image sensor havinghigh resolution. Further, it is possible to increase precision of phasedifference detection and autofocusing control of objects with all of thecolors.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an image sensor according to some exampleembodiments.

FIGS. 2 to 7 are layout views for parts of pixel array units included inimage sensors according to some example embodiments, respectively.

FIGS. 8 to 10 layout views for pixel array units included in imagesensors according to some example embodiments, respectively.

FIG. 11 is a diagram illustrating a connection relation of a pluralityof pixels and a plurality of signal lines included in the image sensoraccording to some example embodiments.

FIG. 12 is an equivalent circuit diagram of two pixels included in theimage sensor according to some example embodiments.

FIGS. 13 and 14 are timing diagrams of a driving signal applied to onerow of a pixel array unit included in the image sensor according to someexample embodiments, respectively.

FIG. 15 is a diagram illustrating a connection relation between aplurality of pixels and a plurality of signal lines included in theimage sensor according to some example embodiments.

FIG. 16 is an equivalent circuit diagram of two pixels included in theimage sensor according to some example embodiments.

FIG. 17 is a schematic top plan view of two pixels included in the imagesensor according to some example embodiments.

FIG. 18 is a cross-sectional view illustrating the image sensorillustrated in FIG. 17 taken along line XVIII-XVIIIa.

FIG. 19 is a cross-sectional view of two pixels included in the imagesensor according to some example embodiments.

FIG. 20 is a layout view of a pixel array unit included in the imagesensor according to some example embodiments.

FIG. 21 is a cross-sectional view illustrating two pixels of the pixelarray unit illustrated in FIG. 20 taken along lines A-A1 and A1-A2.

FIG. 22 is a layout view of a pixel array unit included in an imagesensor according to some example embodiments.

FIG. 23 is a cross-sectional view illustrating two pixels of the pixelarray unit illustrated in FIG. 22 taken along lines B-B1 and B1-B2.

FIG. 24 is a schematic block diagram of an electronic device includingan image sensor according to some example embodiments.

DETAILED DESCRIPTION

An image sensor according to some example embodiments will be describedwith reference to FIGS. 1 and 2.

An image sensor 1 according to some example embodiments includes a pixelarray unit 300, a first driver 400, a second driver 500, and a timingcontroller 600.

The pixel array unit 300 includes a plurality of pixels Px and aplurality of signal lines (not illustrated). The plurality of pixels Pxmay be arranged in a matrix form, but is not limited thereto. When theplurality of pixels Px may be arranged in a matrix form, a row directionis referred to as a first direction Dr1, and a column direction isreferred to as a second direction Dr2. A direction vertical to both thefirst direction Dr1 and the second direction Dr2 is referred to as athird direction Dr3.

Each pixel Px may receive a driving signal Sr from the first driver 400,and convert incident light into an electric signal and generate andoutput a pixel signal Sp. The driving signal Sr may include a selectionsignal, a reset signal, a transmission signal, and the like.

Each pixel Px may include a plurality of sub areas Pa and Pb each ofwhich includes a plurality of photoelectric conversion elements. Theplurality of photoelectric conversion elements positioned in each of theplurality of sub areas Pa and Pb may be spaced apart from each other ina plane structure, and each photoelectric conversion element may detectand photoelectrically convert incident light. The photoelectricconversion element may be, for example, a photodiode, a pinnedphotodiode, a photogate, and/or a phototransistor. The description belowis given based on a case where the photoelectric conversion element is aphotodiode as an example.

FIGS. 1 and 2 illustrate an example, in which one pixel Px includes thetwo sub areas Pa and Pb, that is, a first sub area Pa and a second subarea Pb, but the number of sub areas Pa Pb included in one pixel Px isnot limited thereto. When one pixel Px includes the two sub areas Pa andPb, the two sub areas Pa and Pb may be arranged while being adjacent toeach other in the first direction Dr1.

Each pixel Px including the plurality of sub areas Pa and Pb maygenerate a first sub pixel signal and a second sub pixel signalcorresponding to photocharges accumulated by the plurality ofphotoelectric conversion elements, respectively, and output thegenerated first sub pixel signal and second sub pixel signal with a timedivisional manner or simultaneously. Each pixel Px may further include areadout element (not illustrated) for processing and outputting thesignal generated by the photoelectric conversion of the photoelectricconversion element.

The pixel array unit 300 may further include a micro-lens ML, whichcorresponds to and overlaps the pixel Px. In the present description,when two constituent elements overlap, an overlapping direction may meanan overlapping in a cross-sectional direction or the third direction Dr3unless otherwise described. The micro-lens ML may collect light and makethe collected light be incident to the pixel Px. The two sub areas Paand Pb included in one pixel Px correspond to and overlap one micro-lensML, and an image is focused on each of the two sub areas Pa and Pbthrough one micro-lens ML.

Referring to FIG. 1, four pixels Px adjacent in a quadrangular shape mayform one pixel unit PU, and the plurality of pixel units PU in the pixelarray unit 300 may be arranged in a matrix form.

The plurality of pixels Px may transmit the pixel signal SP, which isgenerated by detecting light, to the second driver 500. Particularly,the plurality of pixels Px may include different pixels Px which detectlight of different colors and outputs pixel signals Sp. Contrary tothis, one pixel Px may temporarily divide and output or simultaneouslyoutput the plurality of pixel signals Sp, which are generated bydetecting light of a plurality of colors.

FIGS. 1 and 2 illustrate an example, in which one pixel Pxphotoelectrically converts light of one color among the plurality ofcolors and generates a pixel signal. In this case, each pixel Px mayinclude a color filter which selectively allows light of a correspondingspecific color to pass. The color filter may be positioned between themicro-lens ML and the photoelectric conversion element in a planestructure.

The color of light, which may be detected by each pixel Px, may be, forexample, one among four colors including a first color C1, a secondcolor C2, a third color C3, and a fourth color C4. Each of the firstcolor C1, the second color C2, the third color C3, and the fourth colorC4 may be a color in a specific wavelength region. For example, thefirst color C1, the second color C2, the third color C3, and the fourthcolor C4 may be blue, white, green, and red, respectively, and an orderthereof may be changed. According to some example embodiments, the firstcolor C1, the second color C2, the third color C3, and the fourth colorC4 may be yellow, white, magenta, and cyan, respectively, and an orderthereof may be changed.

One color or two colors among the first color C1, the second color C2,the third color C3, and the fourth color C4 may also be omitted. In thiscase, one pixel unit PU may include at least one pair of pixels Px,which are capable of detecting (and/or configured to detect) light ofthe same color, and a pair of pixels Px for the same color may beadjacent to each other in a diagonal direction in the pixel unit PU. Forexample, in FIG. 2, the second color C2 and the third color C3 may bethe same color, and the same color may be white or green. Further, inFIG. 2, the first color C1 and the fourth color C4 may also be the samecolor.

In the pixel array unit 300, the pixel unit PU having the same colordisposition may also be repeatedly disposed in the first direction Dr1and the second direction Dr2, and at least two types of pixel units PUhaving different color dispositions may also be alternately disposed inthe first direction Dr1 and/or the second direction Dr2.

When the second color C2 is white, the amount of light, which thephotoelectric conversion element of the pixel Px receives, may beincreased, so that total sensitivity of the image sensor 1 may beincreased. Accordingly, there is room for further decreasing a size ofthe pixel Px, so that it is possible to increase resolution of the imagesensor 1 without the degradation of sensitivity. For example, when awidth of one pixel Px is decreased to about 1.22 micrometers, it ispossible to maintain sensitivity of the image sensor 1 at low luminance.

At least one pixel Px among the total pixels Px included in the pixelarray unit 300 may be an autofocusing pixel PF, which is capable ofdetecting (and/or configured to detect)a phase difference forcontrolling autofocusing, and the remaining pixels Px may be normalpixels PN which are not used for the autofocusing control. FIG. 1illustrates an example, in which two pixels Px adjacent in the diagonaldirection in one pixel unit including four pixels Px adjacent in aquadrangular shape are autofocusing pixels PF. That is, the autofocusingpixel PF and the normal pixel PN may be alternately positioned in eachrow and each column. However, the disposition of the autofocusing pixelPF is not limited to the illustration. In the drawing, the autofocusingpixel PF is indicated with gray hatching, and this is applied to theentire drawings. Signals readout from the autofocusing pixel PF may bereferred to as autofocusing pixel signals. Signals readout from thenormal pixel PN may be referred to as normal pixel signals.

The autofocusing pixel PF may output the first sub pixel signal and thesecond sub pixel signal, which are generated as a result of thephotoelectric conversion in the two sub areas Pa and Pb, in which onemicro-lens ML is positioned, with a time division, and detect a phasedifference in the first direction Dr1 by comparing the first and secondsub pixel signals. It is possible to measure a distance to an object byusing the detected phase difference, and determine whether the object isin focus and the degree by which the object is out of focus.

The normal pixel PN may collect charges, which are generated as a resultof the photoelectric conversion in the two sub areas Pa and Pb andoutput one pixel signal corresponding to the collected charges, therebydecreasing a readout time of the pixel signal Sp.

The colors detectible by the autofocusing pixels PF may be a portion ofthe plurality of colors detectible by the entire pixels Px. That is,only the pixel signals Sp for some colors among the pixel signals Sp forthe light of the different colors output by the pixel array unit 300 maybe used for detecting a phase difference for the autofocusing control.

For example, the autofocusing pixels PF may include only the pixel ofthe second color C2 as illustrated in FIG. 2, or may further include apixel Px of a different color other than the second color C2.

The kind of color detected by the autofocusing pixel PF may be differentaccording to a color condition, such as a feeling of color and a colortemperature, of an object which the image sensor 1 desires to mainlysense. In general, the color detected by the autofocusing pixel PF maybe white and/or green, and may further include other colors.

When the autofocusing pixel PF includes the pixel of the second color C2that is white, it is possible to detect a phase difference and performthe autofocusing function for all colors of the objects, and sensitivityof the autofocusing pixel PF may be increased. Accordingly, it ispossible to improve precision of the phase detection for the objects ofall of the colors and precision of the autofocusing control.Simultaneously, all of the pixels Px included in the pixel array unit300 includes the plurality of sub areas Pa and Pb, so that a processcondition of forming all of the pixels Px in the manufacturing processof the pixel array unit 300 is uniform. Thus, a manufacturing method issimple. A yield may be increased, and a characteristic deviation betweenthe plurality of pixels Px of the image sensor 1 is reduced and/orminimized to and obtain uniform image data.

According to some example embodiments, even when one pixel Px outputsthe pixel signals Sp for the light of the plurality of colors with thetime division or during the same time, only the pixel signals Sp forsome colors among the pixel signals Sp for the light of the plurality ofcolors output by the pixel array unit 300 may be used in the phasedifference detection for the autofocusing control. Even in this case,some pixels Px among the entire pixels Px included in the pixel arrayunit 300 may correspond to the autofocusing pixels PF. This will bedescribed in more detail below.

Referring back to FIG. 1, the first driver 400 supplies the drivingsignal Sr, such as a selection signal, a reset signal, and atransmission signal, to the plurality of pixels Px.

The second driver 500 may receive and process the pixel signal Spgenerated by each of the plurality of pixels Px and generate image data.The second driver 500 may include a correlated double sampler (notillustrated), which receives a pixel signal Sp and removes a specificnoise for each column, an analog-digital converting (ADC) unit (notillustrated), which is capable of analog-digital converting the signal(and/or configured to analog-digital convert) the signal, in which thenoise is removed, or performing a calculation between sub pixel signals,a temporal memory (not illustrated), which stores the digital convertedsignal, a buffer (not illustrated), which amplifies the digitalconverted signal and outputs the amplified signal as image data, and thelike. The second driver 500 may further include an image data processor(not illustrated), which receives and processes image data. The imagedata processor may obtain phase difference information about theautofocusing pixel PF, information on a distance to an object andinformation on a focus from the image sensor 1, and the like.

The timing controller 600 provides a timing signal and a control signalto the first driver 400 and the second driver 500 and controls theoperations of the first driver 400 and the second driver 500.

Then, an example structure of the pixel array unit 300 of the imagesensor according to some example embodiments will be described withreference to FIGS. 3 to 10 together with FIGS. 1 and 2.

Referring to FIG. 3, one pixel unit PU may include a pair of whitepixels W which are adjacent to each other in one diagonal direction, anda blue pixel B and a red pixel R which are adjacent to each other inanother diagonal direction. According to some example embodiments, thewhite pixels W detecting white light among the plurality of pixels Pxincluded in the pixel array unit 300 are the autofocusing pixels PF, andthe blue pixel B detecting blue light and the red pixel R detecting redlight may be the normal pixels PN. According to some exampleembodiments, the autofocusing pixel PF includes the white pixel W, sothat it is possible to perform the phase difference detection and theautofocusing function on the objects of all of the colors, andsensitivity of the autofocusing pixel PF is relatively high, so that itis possible to increase precision of the phase detection for the objectsof all of the colors and precision of the autofocusing control.

According to some example embodiments, positions of the red pixel R andthe blue pixel B may also be changed in FIG. 3.

According to some example embodiments, one pixel unit PU may alsoinclude a pair of green pixels G instead of the pair of white pixels Win FIG. 3. In this case, the green pixels G may be the autofocusingpixels PF, and the blue pixel B and the red pixel R may be the normalpixels PN.

According to some example embodiments, the kind of color of the lightdetected by the autofocusing pixel PF may be different depending on arow. For example, in FIG. 3, a row, in which the white pixel W is theautofocusing pixel PF and a row, in which the blue pixel B or the redpixel R is the autofocusing pixel PF, may be alternately arranged in thesecond direction Dr2. According to this, it is possible to increaseprecision of the phase difference detection and the autofocusing controlby using a pixel of a specific color (e.g., the red pixel R or the bluepixel B), other than the white pixel W, according to a colorcharacteristic of an environment, in which the image sensor 1 is used.

According to some example embodiments, in FIG. 3, one pixel unit PU mayalso include two pixels selected from a yellow pixel (not illustrated),which is capable of detecting (and/or configured to detect) yellowlight, a cyan pixel (not illustrated), which is capable of detecting(and/or configured to detect) cyan light, and a magenta pixel, which iscapable of detecting (and/or configured to detect) magenta light,instead of the red pixel R or the blue pixel B.

Referring to FIG. 4, one pixel unit PU may include four pixels Pxdetecting light of different colors, for example, white W, red R, greenG, and blue B. In this case, the white pixel W and the green pixel Gdetecting green light may be adjacent to each other in one diagonaldirection. According to some example embodiments, the white pixel Wamong the plurality of pixels Px included in the pixel array unit 300may be the autofocusing pixel PF, and the blue pixel B, the green pixelG, and the red pixel R may be the normal pixels PN.

According to some example embodiments, the green pixel G in theexemplary embodiment illustrated in FIG. 4 may be the autofocusing pixelPF. According to this, the autofocusing pixel PF includes the whitepixel W, so that it is possible to perform the phase differencedetection and the autofocusing function on the objects of all of thecolors, and sensitivity of the green pixel G is high, so that it ispossible to improve precision of the phase detection and precision andperformance of the autofocusing control.

According to some example embodiments, in FIG. 4, one pixel unit PU mayalso include a yellow pixel, a cyan pixel, and a magenta pixel, insteadof the red pixel R, the green pixel G, and the blue pixel B.

The disposition of the pixels Px illustrated in FIGS. 3 and 4 may beapplied to the whole pixel array unit 300 or a part of the pixel arrayunit 300.

Referring to FIGS. 5 to 7, in the pixel array unit 300, an expanded unitincluding four pixel units PU adjacent in a quadrangular shape may berepeatedly disposed in the first direction Dr1 and the second directionDr2. The expanded unit may include 16 pixels Px as illustrated in FIGS.5 to 7.

Referring to FIG. 5, one expanded unit may include a pair of first pixelunits PUa adjacent to each other in one diagonal direction, and a pairof second pixel units PUb adjacent to each other in the other diagonaldirection. The first pixel unit PUa may include a pair of white pixels Wadjacent to each other in one diagonal direction and a pair of greenpixels G adjacent to each other in the other diagonal direction. Thesecond pixel unit PUb may include a pair of white pixels W adjacent toeach other in one diagonal direction and a red pixel R and a blue pixelB adjacent to each other in the other diagonal direction.

Referring to FIG. 6, one expanded unit may include a pair of first pixelunits PUa adjacent to each other in one diagonal direction, and a thirdpixel unit PUc and a fourth pixel unit PUd adjacent to each other in theother diagonal direction. The first pixel unit PUa is the same as thosedescribed above. The third pixel unit PUc may include a pair of whitepixels W adjacent to each other in one diagonal direction and a pair ofblue pixels B adjacent to each other in the other diagonal direction.The fourth pixel unit PUd may include a pair of white pixels W adjacentto each other in one diagonal direction and a pair of red pixels Radjacent to each other in the other diagonal direction.

Referring to FIG. 7, one expanded unit may include a pair of first pixelunits PUa adjacent to each other in one diagonal direction, and a fifthpixel unit PUe and a sixth pixel unit PUf adjacent to each other in theother diagonal direction. The first pixel unit PUa is the same as thosedescribed above. The fifth pixel unit PUe may include a pair of whitepixels W adjacent to each other in one diagonal direction and a redpixel R and a green pixel G adjacent to each other in the other diagonaldirection. The sixth pixel unit PUf may include a pair of white pixels Wadjacent to each other in one diagonal direction and a blue pixel B anda green pixel G adjacent to each other in the other diagonal direction.

In some example embodiments, as illustrated in FIGS. 5 to 7, only somepixels may be the autofocusing pixels PF. For example, only the whitepixel W may be the autofocusing pixel PF, or both the white pixels W andthe green pixel G may also be the autofocusing pixels PF.

Referring to FIGS. 8 and 9, a pixel unit PU1 including the autofocusingpixel PF may be limited to and positioned in an autofocusing pixel areaPFA that is a specific area of the pixel array unit 300. All of thepixel units PU2 positioned in a region other than the autofocusing pixelarea PFA may include the normal pixels PN.

The autofocusing pixel area PFA may also be limited to and positioned ata center portion of the pixel array unit 300 as illustrated in FIG. 8,and may also be formed in a cross shape including a horizontal portionand a vertical portion, which cross the pixel array unit 300 indifferent directions, as illustrated in FIG. 9.

Referring to FIG. 8, the color disposition of the pixels Px positionedin the region, except for the autofocusing pixel area PFA may bedifferent from the color disposition in the autofocusing pixel area PFA.Particularly, referring to FIG. 8, the pixel unit PU1 positioned in theautofocusing pixel area PFA may include a pair of white pixels Wadjacent to each other in the diagonal direction, and the pixel unit PU2positioned in the region, except for the autofocusing pixel area PFA,may include a pair of green pixels G adjacent to each other in thediagonal direction. In the autofocusing pixel area PFA, the white pixelW may be the autofocusing pixel PF.

As illustrated in FIG. 8, when an image is detected by using the whitepixel W as the autofocusing pixel PF in the autofocusing pixel area PFA,and disposing the large number of green pixels G in the remainingregion, except for the autofocusing pixel area PFA, it is possible toincrease precision of the phase detection and the autofocusing controlbased on high sensitivity of the white pixel W in the autofocusing pixelarea PFA, and simultaneously improve a feeling of color of detectedimage data because the pixels Px of the entire colors including thegreen pixel G are used in the region except for the autofocusing pixelarea PFA.

According to some example embodiments, the color disposition of thepixels Px of the pixel unit PU2 positioned in the region except for theautofocusing pixel area PFA may also be the same as the colordisposition of the pixel unit PU1 in the autofocusing pixel area PFA.

Referring to FIG. 10, the pixel units PU1 including the autofocusingpixels PF in the pixel array unit 300 may be distributed while beingspaced apart from each other. In this case, the pixel unit PU2 otherthan the pixel unit PU1 may have a different color disposition from thatof the pixel unit PU1 including the autofocusing pixel PF as illustratedin FIG. 10. For example, the pixel unit PU1 including the autofocusingpixel PF may include a pair of white pixels W adjacent to each other inthe diagonal direction, and the pixel unit PU2 including only the normalpixels PN may include a pair of green pixels G adjacent to each other inthe diagonal direction, instead of the white pixels W. In the pixel unitPU1, the white pixel W may be the autofocusing pixel PF.

Unlike FIG. 10, the color disposition of the pixel unit PU1 includingthe autofocusing pixel PF may also be the same as the color dispositionof the pixel unit PU2 including only the normal pixel PN.

An example structure of the pixel array unit 300 and a structure of thepixel Px according to some example embodiments will be described withreference to FIGS. 11 and 12 together with the aforementioned drawings.

Referring to FIG. 11, each pixel Px includes a plurality of first andsecond photoelectric conversion elements PD1 and PD2 each of which iscapable of independently photoelectrically converting light (and/orconfigured to independently convert light).

A plurality of signal lines included in the pixel array unit 300 mayinclude a power voltage line VDL, a plurality of transmission signallines TGL1, TGL2, and TGL3, a reset signal line RGL, and a selectionsignal line SELL that are disposed every at least one row, and outputsignal lines RL1 and RL2 disposed by every at least one column. FIG. 11illustrates an example, in which the power voltage line VDL, theplurality of transmission signal lines TGL1, TGL2, and TGL3, the resetsignal line RGL, and the selection signal line SELL are disposed foreach row, and the output signal lines RL1 or RL2 are disposed by everytwo columns, so that two pixels Px adjacent to each other in the firstdirection Dr1 share one output signal line RL1 or RL2. The two adjacentpixels Px sharing one output signal line RL1 or RL2 may be connected tothe different transmission signal lines TGL1, TGL2, and TGL3.

The power voltage line VDL, the transmission signal lines TGL1, TGL2,and TGL3, the reset signal line RGL, and the selection signal line SELLmay be generally extended in the first direction Dr1, and the outputsignal lines RL1 and RL2 may be extended in a direction (e.g., thesecond direction Dr2) crossing the first direction Dr1.

The power voltage line VDL may transmit a uniform power voltage VDD, andthe plurality of transmission signal lines TGL1, TGL2, and TGL3 disposedin one row may independently transmit transmission signals TG1, TG2, andTG3 and transmit the charges generated in the photoelectric conversionelements PD1 and PD2 of the pixel Px to a readout element (notillustrated). The reset signal line RGL may transmit a reset signal RGfor resetting the pixel Px, and the selection signal line SELL maytransmit a selection signal SEL for directing a row selection. Thetransmission signals TG1, TG2, and TG3, the reset signal RG, and theselection signal SEL may be output from the aforementioned first driver400. The first driver 400 may sequentially or non-sequentially outputthe transmission signals TG1, TG2, and TG3, the reset signal RG, and theselection signal SEL for each row.

The number of transmission signal lines TGL1, TGL2, and TGL3 connectedwith the autofocusing pixel PF may be different from the number oftransmission signal lines TGL1, TGL2, and TGL3 connected with the normalpixel PN. Particularly, the number of transmission signal lines TGL1,TGL2, and TGL3 connected with one normal pixel PN may be smaller thanthe number of transmission signal lines TGL1, TGL2, and TGL3 connectedwith one autofocusing pixel PF or may be generally one. The number oftransmission signal lines TGL1, TGL2, and TGL3 connected with oneautofocusing pixel PF may be changed according to the number ofphotoelectric conversion elements included in one pixel Px. AlthoughFIG. 1 illustrates an example, in which one pixel Px includes twophotoelectric conversion elements PD1 and PD2, inventive concepts arenot limited thereto. In some example embodiments, a pixel may includemore than two photoelectric conversion elements.

Referring to FIG. 11, one autofocusing pixel PF may be connected to thetwo transmission signal lines TGL1 and TGL2, and the normal pixel PN maybe connected to one transmission signal line TGL3. The transmissionsignal line TGL3 connected with the normal pixel PN may be a differenttransmission signal line from the transmission signal lines TGL1 andTGL2 connected with the autofocusing pixel PF positioned in the samerow. Particularly, between the autofocusing pixel PF and the normalpixel PN positioned in one row and connected to the same output signalline RL1 or RL2, the autofocusing pixel PF may be connected to the firstand second transmission signal lines TGL1 and TGL2, and the normal pixelPN may be connected to the third transmission signal line TGL3.

Although not illustrated, when there exists a row including only thenormal pixel PN, one of the two adjacent normal pixels PN connected tothe same output signal line RL1 or RL2 may be connected to one of thefirst to third transmission signal lines TGL1, TGL2, and TGL3, and theother may be connected to one of the remaining transmission signal linesTGL1, TGL2, and TGL3. A connection relation between the pixel Px and thesignal line may be variously changed.

The pixels Px positioned in the same row may be connected to the samereset signal line RGL and the same selection signal line SELL.

An example of a circuit structure of one pixel Px will be described withreference to FIG. 12.

In FIG. 12, one pixel Px includes the first and second photoelectricconversion elements PD1 and PD2, and a readout element for reading outphotoelectric conversion signals of the first and second photoelectricconversion elements PD1 and PD2. The readout element may include firstand second transmission transistors TX1 and TX2 connected between afloating diffusion node FD and the first and second photoelectricconversion elements PD1 and PD2, a reset transistor RX and a drivingtransistor DX connected between the floating diffusion node FD and thepower voltage line VDL, and a selection transistor SX connected betweenthe driving transistor DX and the output signal line RL1.

Each of the first and second photoelectric conversion elements PD1 andPD2 may be a photodiode including an anode connected to a common voltageVSS. A cathode of the photodiode is connected to the first and secondtransmission transistors TX1 and TX2. Charges generated through thereception of light by the first and second photoelectric conversionelements PD1 and PD2 may be transmitted to the floating diffusion nodeFD through the first and second transmission transistors TX1 and TX2.

Gates of the first and second transmission transistors TX1 and TX2 maybe connected to the transmission signal lines TGL1, TGL2, and TGL3 andreceive the transmission signals TG1, TG2, and TG3. As described above,the gates of the first and second transmission transistors TX1 and Tx2of the autofocusing pixel PF may be connected to the differenttransmission signal lines TGL1 and TGL2, and the gates of the first andsecond transmission transistors TX1 and TX2 of the normal pixel PN maybe connected to the same transmission signal line TGL3. Accordingly, thecharges generated by each of the first and second photoelectricconversion elements PD1 and PD2 of the autofocusing pixel PF may betransmitted to the floating diffusion node FD through the first andsecond transmission transistors TX1 and TX2, which are turned on atdifferent times, and the charges generated by each of the first andsecond photoelectric conversion elements PD1 and PD2 of the normal pixelPN may be transmitted to the floating diffusion node FD through thefirst and second transmission transistors TX1 and TX2, which are turnedon at the same time.

The floating diffusion node FD accumulates and stores the receivedcharges, and the driving transistor DX may be controlled according tothe quantity of charges accumulate din the floating diffusion node FD.

A gate of the reset transistor RX is connected with the reset signalline RGL. The reset transistor RX may be controlled by the reset signalRG transmitted by the reset signal line RGL and periodically reset thefloating diffusion node FD with the power voltage VDD.

The driving transistor DX may output a voltage which is varied inresponse to a voltage of the floating diffusion node FD. The drivingtransistor DX may be combined with a constant current source (notillustrated) to serve as a source follower buffer amplifier. The drivingtransistor DX may generate a source-drain current in proportion to asize of the quantity of charges applied to the gate.

A gate of the selection transistor SX is connected with the selectionsignal line SELL. The selection transistor SX, which is turned onaccording to an activation of the selection signal SEL transmitted bythe selection signal line SELL, may output a current generated in thedriving transistor DX to the output signal line RL1 as a pixel signalSp. The selection signal SEL is a signal selecting a row, which is tooutput the pixel signal Sp, and may be sequentially or non-sequentiallyapplied in a unit of the row.

Unlike the illustration of FIG. 12, each of the first and secondtransmission transistors TX1 and TX2 in one pixel Px may be connected toa separate floating diffusion node (not illustrated), without beingconnected to the same floating diffusion node FD.

Then, a method of driving the image sensor according to some exampleembodiments during one frame will be described with reference to FIGS.13 and 14 together with aforementioned FIG. 12.

First, when an activated selection signal SEL having a gate-on voltagelevel is applied to the selection signal line SELL, a selectiontransistor SX positioned in a selected row is turned on. When anactivated reset signal RG is applied to the reset signal line RGL in theturn-on state of the selection transistor SX, the reset transistor RXpositioned in the corresponding row is turned on, the charges of thefloating diffusion node FD are discharged, and the floating diffusionnode FD is reset, and a reset output signal corresponding to charges ofthe reset floating diffusion node FD is output to the output signal lineRL1 through the driving transistor DX and the selection transistor SX.

Next, when the reset transistor RX is turned off and an activatedtransmission signal TG1 is applied to the first transmission signal lineTGL1 at a first timing t1, the first transmission transistor TX1 of theautofocusing pixel PF is turned on and photoelectrically convertedcharges of the first photoelectric conversion element PD1 aretransmitted to the floating diffusion node FD. Then, a first sub pixelsignal corresponding to the photoelectrically converted signal of thefirst sub area Pa of the autofocusing pixel PF is output to the outputsignal line RL1 through the driving transistor DX and the turned-onselection transistor SX.

Then, when an activated transmission signal TG2 is applied to the secondtransmission signal line TGL2 at a second timing t2 after the firsttiming t1, the second transmission transistor TX2 of the autofocusingpixel PF is turned on and photoelectrically converted charges of thesecond photoelectric conversion element PD2 are transmitted to thefloating diffusion node FD. Then, a first sub pixel signal correspondingto the photoelectrically converted signal of the first sub area Pb ofthe autofocusing pixel PF is output to the output signal line RL1through the driving transistor DX and the turned-on selection transistorSX.

In this case, as illustrated in FIG. 13, the activated transmissionsignal TG1 having the gate-on voltage level is also transmitted to thefirst transmission signal line TGL1 at the second timing t2, at whichthe activated transmission signal TG2 having the gate-on voltage levelis transmitted to the second transmission signal line TGL2, so that thefirst and second transmission transistors TX1 and TX2 of theautofocusing pixel PF may be simultaneously turned on. That is, thetransmission signal TG1 applied to one row during one frame may beactivated two times, and the transmission signal TG2 may be activatedone time. Then, the photoelectrically converted charges of the first andsecond photoelectric conversion elements PD1 and PD2 of the autofocusingpixel PF may be transmitted to the floating diffusion node FD together,and a pixel signal corresponding to a sum of the first and second subpixel signals may be output to the output signal line RL1.

Alternatively, as illustrated in FIG. 14, when the activatedtransmission signal TG2 is transmitted to the second transmission signalline TGL2 at the second timing t2, the first transmission signal lineTGL1 may be inactivated and only the second transmission transistor TX2of the autofocusing pixel PF may be turned on, the photoelectricallyconverted charges of the second photoelectric conversion element PD2 maybe transmitted to the floating diffusion node FD, and only the secondsub pixel signal may be output to the output signal line RL1.

Then, when an activated transmission signal TG3 having a gate-on voltagelevel is transmitted to the third transmission signal line TGL3 at athird timing t3 in the turn-off state of the first and secondtransmission transistors TX1 and TX2 of the autofocusing pixel PF, thefirst and second transmission transistors TX1 and TX2 of the normalpixel PN are simultaneously turned on and the photoelectricallyconverted charges of the first and second photoelectric conversionelements PD1 and PD2 of the normal pixel PN are transmitted to thefloating diffusion node FD together. Then, a pixel signal according tothe quantity of charges accumulated in the floating diffusion node FD isoutput to the output signal line RL1 through the driving transistor DXand the turned-on selection transistor SX.

The second driver 500 may remove a noise from the pixel signal or thefirst and second sub pixel signals through a subtraction between thereset output signal and the pixel signal or the first and second subpixel signals. Further, in a case of the driving method according tosome example embodiments illustrated in FIG. 13, the second driver 500may obtain the second sub pixel signal through a subtraction of thefirst sub pixel signal from the sum of the first and second sub pixelsignals output at different times from the autofocusing pixel PF. It ispossible to obtain image data of the corresponding autofocusing pixel PFby using the sum of the first and second sub pixel signals obtained forthe autofocusing pixel PF, and obtain image data of the correspondingnormal pixel PN by using the pixel signal obtained for the normal pixelPN.

It is possible to detect a phase difference between light incident tothe first and second sub areas Pa and Pb of the autofocusing pixel PF byusing the obtained first and second sub pixel signals. It is possible toobtain focus information, such as a distance to an object, whether theobject is in focus, and the degree by which the object is out of focus,by using the detected phase difference. Further, the first and secondtransmission transistors TX1 and TX2 are simultaneously driven by usingone transmission signal TG3 and one pixel signal is read out for thenormal pixel PN, so that an entire readout rate of the image sensor 1may be increased. That is, according to some example embodiments, forthe normal pixel PN including the plurality of sub areas Pa and Pb, areadout time may be decreased to about ¾, compared to a case where theplurality of different transmission signals is transmitted like theautofocusing pixel PF.

Next, another example of the pixel array unit 300 and a structure of thepixel PX according to some example embodiments will be described withreference to FIGS. 15 and 16 together with the aforementioned drawings.Descriptions of the same constituent elements as those described abovewill be omitted.

Referring to FIG. 15, the structure of the pixel array unit 300according to some example embodiments is mostly the same as the pixelarray unit 300 in FIG. 11, but the first and second transmission signallines TGL1 and TGL2 may be disposed for each row, and the output signallines RL1, RL2, RL3, or RL4 may be disposed for every column, so thatthe two pixels Px adjacent to each other in the first direction Dr1 maybe connected to the different output signal lines RL1, RL2, RL3, andRL4.

The autofocusing pixel PF is connected to the two transmission signallines TGL1 and TGL2, so that the first and second photoelectricconversion elements PD1 and PD2 included in the autofocusing pixel PFmay transmit photoelectrically converted charges to the floatingdiffusion node FD at different timings. Unlike, the normal pixel PN maybe connected to one transmission signal line TGL1 or TGL2. Accordingly,the first and second photoelectric conversion elements PD1 and PD2included in the normal pixel PN may transmit photoelectrically convertedcharges to the floating diffusion node FD at the same timing. Thetransmission signal lines TGL1 connected with the normal pixel PN may bethe same as one of the transmission signal lines TGL1 and TGL2 connectedwith the autofocusing pixel PF positioned in the same row. FIG. 15illustrates an example, in which the normal pixel PN is connected to thefirst transmission signal line TGL1, but the normal pixel PN is notlimited thereto, and may also be connected to the second transmissionsignal line TGL2.

Although not illustrated, when one row includes only the normal pixelPN, all of the normal pixels PN positioned in the row may be connectedto one of the two transmission signal lines TGL1 and TGL2.

FIG. 16 illustrates a circuit structure of one pixel Px according tosome example embodiments illustrated in FIG. 15, and the circuitstructure of each pixel Px is the same as that illustrated in FIG. 12,so that a detailed description thereof will be omitted.

Next, an example structure of an image sensor according to some exampleembodiments will be described with reference to FIGS. 17 and 18 togetherwith the aforementioned drawings. Descriptions of the same constituentelements as those described above will be omitted.

Referring to FIGS. 17 and 18, the image sensor according to some exampleembodiments may include a semiconductor substrate 120 having a firstsurface BS and a second surface FS facing each other. The semiconductorsubstrate 120 may be a substrate including, for example, silicon,germanium, silicon-germanium, a Group VI compound semiconductor, and aGroup V compound semiconductor. The semiconductor substrate 120 may be asilicon substrate, into which P-type or N-type impurities are injected.Here, an example will be described based on the semiconductor substrate120, into which P-type impurities are injected, as an example.

Here, the semiconductor substrate 120 may include a plurality ofphotoelectric conversion elements PD1 and PD2, a floating diffusion node(not illustrated) region, and the like positioned in each pixel Px. Thefloating diffusion node region may be formed of, for example, a region,in N-type impurities are doped.

Each of the photoelectric conversion elements PD1 and PD2 may beconfigured by a PN junction, and a pair of electron and hole may begenerated according to incident light to generate photocharges. Thephotoelectric conversion elements PD1 and PD2 may be formed byion-injecting impurities, for example, N-type impurities, having anopposite conduction type to that of the semiconductor substrate 120,into the semiconductor substrate 120. The photoelectric conversionelements PD1 and PD2 may also be formed in a form, in which a pluralityof doping regions may be laminated.

The semiconductor substrate 120 may include a first isolator 122, whichmay be positioned between the adjacent pixels Px, particularly, betweenan autofocusing pixel PF and a normal pixel PN to divide the adjacentpixels Px. The first isolator 122 may surround each pixel Px on a planeas illustrated in FIG. 17.

The first isolator 122 may be deeply formed in a third direction Dr3 ina cross-section structure as illustrated in FIG. 18. For example, thefirst isolator 122 may also pass through the semiconductor substrate 120in the third direction Dr3, and may be positioned within thesemiconductor substrate 120 while an upper surface of the first isolator122 meets a first surface BS of the semiconductor substrate 120 and alower surface of the first isolator 122 does not meet a second surfaceFS of the semiconductor substrate 120.

The semiconductor substrate 120 may further include a second isolator124, which may be positioned between the first and second photoelectricconversion elements PD1 and PD2 adjacent to each other within one pixelPx and divides the first and second photoelectric conversion elementsPD1 and PD2. The second isolator 124 may be approximately extended inthe second direction Dr2 in a plane structure, but is not limitedthereto. The second isolator 124 may also be connected to the firstisolator 122 on a plane as illustrated in FIG. 17, and may also bespaced apart from the first isolator 122.

Referring to FIG. 18, a depth of the second isolator 124 in the thirddirection Dr3 may be smaller than or equal to a depth of the firstisolator 122 in the third direction Dr3. As illustrated in FIG. 18, anupper surface of the second isolator 124 may meet the first surface BSof the semiconductor substrate 120, and a lower surface thereof may bepositioned within the semiconductor substrate 120.

At least one of the first isolator 122 and the second isolator 124 mayinclude an insulating material, such as oxide, nitride and polysilicon,or a combination thereof. In this case, at least one of the firstisolator 122 and the second isolator 124 may be formed by forming atrench by patterning the semiconductor substrate 120 at the firstsurface BS side or the second surface FS side and then burying theinsulating material in the trench.

According to some example embodiments, at least one of the firstisolator 122 and the second isolator 124 may also be formed byion-injecting impurities, for example, P-type impurities, having anopposite conductive type to that of the first and second photoelectricconversion elements PD1 and PD2, into the semiconductor substrate 120.In this case, a concentration of impurities of at least one of the firstisolator 122 and the second isolator 124 may be higher than aconcentration of impurities of the semiconductor substrate 120 around atleast one of the first isolator 122 and the second isolator 124.

According to some example embodiments, the first isolator 122 mayinclude an insulating material, such as an oxide, a nitride, andpolysilicon, and the second isolator 124 may be doped with impurities.Particularly, the second isolator 124 may be doped with the impuritieshaving the same conductive type as the impurities of the semiconductorsubstrate 120 around the second isolator 124 with a higherconcentration.

The first isolator 122 may limit and/or prevent an electric crosstalkbetween the adjacent pixels Px by limiting and/or blocking a movement ofthe charges between the adjacent pixels Px, and may also limit and/orprevent an optical crosstalk which may occur due to the pass of lightthrough the adjacent pixel Px by refracting light slantly (and/ordiagonally) incident to one pixel Px. The second isolator 124 may limitand/or prevent an electric crosstalk between the adjacent photoelectricconversion elements PD1 and PD2 by limiting and/or blocking a movementof the charges between the adjacent photoelectric conversion elementsPD1 and PD2, and may also limit and/or prevent an optical crosstalkwhich may occur due to the pass of light through the differentphotoelectric conversion element PD1 or PD2 within the same pixel Px byrefracting light slantly (and/or diagonally) incident to onephotoelectric conversion element PD1 or PD2. Particularly, the secondisolator 124 positioned in the autofocusing pixel PF may limit and/orprevent an electrical and optical crosstalk between the first and secondphotoelectric conversion elements PD1 and PD2, thereby increasingprecision of the phase difference detection and precision of theautofocusing control.

At least one of the first isolator 122 and the second isolator 124 mayalso be omitted according to a design condition of the image sensor.

A plurality of color filters 131 and 132 and a micro-lens ML may bepositioned on the first surface BS of the semiconductor substrate 120.One color filter 131 or 132 and one micro-lens ML may be positioned soas to correspond to each pixel to overlap both the first photoelectricconversion element PD1 and the second photoelectric conversion elementPD2 included in one pixel Px in the third direction Dr3.

The color filters 131 and 132 positioned in the adjacent pixels Px,respectively, may select light of different colors and allow the lightto pass through. Each of the color filters 131 and 132 may selectivelyallow light of blue, green, and red to pass through, or selectivelyallow light of magenta, yellow, cyan, and the like to pass through, orallow light of white to pass through. The white color filters 131 and132 may be transparent and allow light of all of the color wavelengthsto pass through. The color filters 131 and 132 may also be omitted.

A wiring layer 110 may be positioned on the second surface FS of thesemiconductor substrate 120. The wiring layer 110 may include aplurality of transistors included in the pixel Px and several wiresconnected to the plurality of transistors. Unlike the illustration inFIG. 18, the wiring layer 110 may also be (or may alternatively)positioned between the semiconductor substrate 120 and the color filters131 and 132.

An insulating layer 140 may be further positioned between the firstsurface BS of the semiconductor substrate 120 and the color filters 131and 132. The insulating layer 140 may limit and/or prevent incidentlight from being reflected and efficiently allow the incident light topass through, thereby improving performance of the image sensor.

According to some example embodiments, the wiring layer 110 may also be(or may alternatively) positioned between the color filters 131 and 132and the semiconductor substrate 120.

Next, an example structure of an image sensor according to some exampleembodiments will be described with reference to FIG. 19 together withthe aforementioned drawings. The same descriptions of the sameconstituent elements as those described above will be omitted.

One pixel Px of the image sensor according to some example embodimentsillustrated in FIG. 19 may include a plurality of photoelectricconversion elements laminated in the third direction Dr3. For example,one pixel Px may include an organic photoelectric conversion element OPDand photoelectric conversion elements PD3 and PD4 formed on asemiconductor substrate 120A.

The organic photoelectric conversion element OPD may be positioned on afirst surface BS of the semiconductor substrate 120A. One organicphotoelectric conversion element OPD may include an organicphotoelectric conversion layer 160, which is selectively detecting lightof a specific color wavelength region, and one first electrode 151 andone second electrode 171 positioned on both surfaces of the organicphotoelectric conversion layer 160.

The organic photoelectric conversion layer 160 may be continuouslyformed over the plurality of pixels Px. A wavelength region of light,which the organic photoelectric conversion layer 160 may detect andphotoelectrically convert, may be, for example, light in a greenwavelength band, but is not limited thereto. The organic photoelectricconversion layer 160 may include a P-type semiconductor and an N-typesemiconductor, and the P-type semiconductor and the N-type semiconductormay form a PN junction. At least one of the P-type semiconductor and theN-type semiconductor may include an organic material.

One first electrode 151 may be positioned for each organic photoelectricconversion element OPD, and the first electrodes 151 of the adjacentorganic photoelectric conversion elements OPD may be spaced apart fromeach other and electrically isolated from each other.

The second electrode 171 may be continuously formed over the pluralityof pixels Px. That is, the second electrode 171 may be continuouslyformed on a front surface of a pixel array unit 300 together with theorganic photoelectric conversion layer 160. The first electrode 151 andthe second electrode 171 may be transparent (e.g., formed of a thin filmincluding a transparent conductive oxide, graphene, carbon nanotubes, athin metal layer of about 50 nm or less, and combinations thereof)

At least one of all of the pixels Px included in the pixel array unitmay be an autofocusing pixel PF and the remaining pixels Px may benormal pixels PN. FIG. 19 illustrates the adjacent autofocusing pixel PFand normal pixel PN.

The autofocusing pixel PF may include a plurality of sub areas Pa andPb, and each of the plurality of sub areas Pa and Pb may include oneorganic photoelectric conversion element OPD. That is, the first subarea Pa of the autofocusing pixel PF may include a first organicphotoelectric conversion element OPD1 including one first electrode 151,and the second sub area Pb of the autofocusing pixel PF may include asecond organic photoelectric conversion element OPD2 including one firstelectrode 151.

Referring to FIG. 19, the first electrode 151 of each of the first andsecond organic photoelectric conversion elements OPD1 and OPD2 may beconnected to a charge storing area 126 of the semiconductor substrate120A through a connection member 115 that is a conductor. The chargesgenerated by the photoelectric conversion by the first and secondorganic photoelectric conversion elements OPD1 and OPD2 may be collectedin the charge storing area 126 through the connection member 115. Theconnection member 115 may include a metal and the like. The chargestoring area 126 may be positioned in a neighboring area of the firstsurface BS of the semiconductor substrate 120A.

Unlike the illustration of FIG. 19, the connection member 115 may alsobe (or may alternatively be) positioned at a place adjacent to a borderof each pixel Px. In this case, the connection member 115 may notoverlap the photoelectric conversion elements PD3 and PD4 of thesemiconductor substrate 120A in a plane structure. Further, theconnection member 115 may be further extended in a down direction and beformed up to the second surface FS of the semiconductor substrate 120A.According to some example embodiments, the connection member 115 mayalso be (or may alternatively be) connected with a conductive member(not illustrated), which is formed from the first surface BS of thesemiconductor substrate 120A to a neighboring area of the second surfaceFS, in the first surface BS. In this case, the charge storing area 126may be positioned in a neighboring area of the second surface FS of thesemiconductor substrate 120A.

The normal pixel PN may not include a plurality of sub areas, and mayinclude one organic photoelectric conversion element OPD.

The semiconductor substrate 120A may include at least one photoelectricconversion element PD3 and PD4 positioned in each pixel Px. Each of thephotoelectric conversion elements PD3 and PD4 positioned in each pixelPx may overlap both the first and second organic photoelectricconversion elements OPD1 and OPD2 of the autofocusing pixel PF in thethird direction Dr3, or may overlap the organic photoelectric conversionelement OPD of the normal pixel PN in the third direction Dr3. Thephotoelectric conversion elements PD3 and PD4 may receive light, whichis left after being photoelectrically converted in the organicphotoelectric conversion element OPD, and photoelectrically convert thereceived light.

FIG. 19 illustrates an example, in which each pixel Px includes thephotoelectric conversion elements PD3 and PD4 positioned in thesemiconductor substrate 120A one by one. Each of the photoelectricconversion elements PD3 and PD4 may receive light of a specificwavelength band and photoelectrically convert the received light. Tothis end, a plurality of color filters 133 and 134 may be positionedbetween the semiconductor substrate 120A and the organic photoelectricconversion element OPD. Colors exhibited by the two color filters 133and 134 positioned in the adjacent pixels Px may be different from eachother. For example, when the organic photoelectric conversion layer 160selectively photoelectrically converts light of a green wavelength band,the color filter 131 positioned in the pixel Px positioned at a leftside in FIG. 19 may selectively allow light of a blue wavelength band inan area other than the green wavelength band to pass through, and thecolor filter 132 positioned in the pixel Px positioned at a right sidein FIG. 19 may selectively allow light of a red wavelength band in thearea other than the green wavelength band to pass through. Accordingly,the photoelectric conversion element PD3 included in the pixel Pxpositioned at the left side in FIG. 19 may detect and photoelectricallyconvert blue light, and the photoelectric conversion element PD4included in the pixel Px positioned at the right side in FIG. 19 maydetect and photoelectrically convert red light. The colors exhibited bythe plurality of color filters 133 and 134 may also be (or mayalternatively be) other colors, other than blue and red.

Unlike the illustration of FIG. 19, each pixel Px may include aplurality of photoelectric conversion elements (not illustrated)overlapping the organic photoelectric conversion element OPD in thethird direction Dr3. The plurality of photoelectric conversion elementspositioned in each pixel Px may overall one another in the thirddirection Dr3. At least one of the plurality of photoelectric conversionelements may also be (or may alternatively be) an inorganicphotoelectric conversion element including a semiconductor material, ormay also be (or may alternatively be) an organic photoelectricconversion element. The plurality of photoelectric conversion elementspositioned in one pixel Px may receive light of a different wavelengthband according to a position thereof.

One micro-lens ML may be positioned on the first and second organicphotoelectric conversion elements OPD1 and OPD2 of each autofocusingpixel PF, and one micro-lens ML may be positioned on the organicphotoelectric conversion element OPD of each normal pixel PN.

An insulating layer 140A may be further positioned between the organicphotoelectric conversion element OPD and the micro-lens ML, and theinsulating layer 140A may be a planarizing layer.

A wiring layer 110A may be positioned between the first surface BS ofthe semiconductor substrate 120A and the organic photoelectricconversion element OPD. The wiring layer 110A may include a plurality oftransistors included in the pixel Px and several wires connected to theplurality of transistors. The signal photoelectrically converted in theorganic photoelectric conversion element OPD and the photoelectricconversion elements PD3 and PD4 may be read out in the wiring layer110A.

The connection member 115 connected with the first electrode 151 of theorganic photoelectric conversion element OPD may be formed while passingthrough an insulating layer 111 included in the wiring layer 110A.

According to some example embodiments, the illustrated wiring layer 110Amay also be (or may alternatively be) positioned under the secondsurface FS of the semiconductor substrate 120A. In this case, a separateinsulating layer (not illustrated) may be positioned between thesemiconductor substrate 120A and the organic photoelectric conversionelement OPD. Further, a conductive connection member (not illustrated)connected with the first electrode 151 of the organic photoelectricconversion element OPD may be formed while passing through theinsulating layer and the semiconductor substrate 120A. In this case, thefirst electrode 151 of the organic photoelectric conversion element OPDmay be connected with the charge storing area (not illustrated) of thesemiconductor substrate 120A through the conductive connection memberand transmit charges.

The first and second organic photoelectric conversion elements OPD1 andOPD2 included in the autofocusing pixel PF may share one floatingdiffusion node (not illustrated) and output the photoelectricallyconverted signal through the same output signal line (not illustrated).

The first and second organic photoelectric conversion elements OPD1 andOPD2 included in the autofocusing pixel PF may be connected to the twotransmission transistors connected to the two transmission signal lines,respectively, like the first and second photoelectric conversionelements PD1 and PD2 of the autofocusing pixel PF illustrated in FIG.12. Accordingly, the first and second organic photoelectric conversionelements OPD1 and OPD2 included in the autofocusing pixel PF may outputthe photoelectrically converted signals of the first and second organicphotoelectric conversion elements OPD1 and OPD2 as first and second subpixel signals at two different timings, respectively, through onefloating diffusion node FD and one driving transistor DX. It is possibleto perform the autofocusing control function by detecting a phasedifference by using the read-out first and second sub pixel signals, andobtain green image data (when the organic photoelectric conversion layerdetects green light) for the corresponding pixel Px in addition to thefirst and second sub pixel signals. In contrast to this, as illustratedin FIG. 14, the photoelectrically converted signal of one of the firstand second organic photoelectric conversion elements OPD1 and OPD2 maybe output at one timing between the two different timings, and thephotoelectrically converted signals of both the first and second organicphotoelectric conversion elements OPD1 and OPD2 may be added and outputat the remaining timing.

It is possible to detect a phase difference between light incident tothe first and second sub areas Pa and Pb of the autofocusing pixel PF byusing the obtained first and second sub pixel signals, and it ispossible to obtain focus information, such as a distance to an object,whether the object is in focus, and the degree by which the object isout of focus, by using the detected phase difference. Further, thecolors detected by the first and second organic photoelectric conversionelements OPD1 and OPD2 included in the autofocusing pixel PF may befreely selected according to a color characteristic, such as the colorsense and a color temperature, of an object, which is to mainly use theautofocusing control function, and thus it is possible to increaseaccuracy of the phase difference detection and the autofocusingfunction.

The organic photoelectric conversion element OPD included in the normalpixel PN may be connected to one transmission signal line and read outone pixel signal.

Although not shown in FIG. 19, the normal pixel PN may also include thefirst and second organic photoelectric conversion elements OPD1 and OPD2like the autofocusing pixel PF. In this case, the first and secondorganic photoelectric conversion elements OPD1 and OPD2 included in thenormal pixel PN may be connected to two transmission transistorsconnected to one transmission signal line, respectively, like the normalpixel PN illustrated in FIG. 12. Accordingly, one pixel signal is readout by using one transmission signal for the normal pixel PN, so that itis possible to increase an entire readout speed of the image sensor.

Next, a pixel array unit 300 included in an image sensor according tosome example embodiments will be described with reference to FIGS. 20and 21 together with the aforementioned drawings.

Referring to FIGS. 20 and 21, the pixel array unit 300 according to someexample embodiments may include a semiconductor substrate 120 includingfirst and second photoelectric conversion elements PD1 and PD2, a wiringlayer 110, a color filter 130, a micro-lens ML, an insulating layer 140,and the like. In some example embodiments, the semiconductor substrate120, the wiring layer 110, the color filter 130, the micro-lens ML, andthe insulating layer 140 are mostly the same as the correspondingconfigurations described above, but a position of a second isolator 124on a plane may be different according to a position of a pixel Px.

In some example embodiments, when the first and second photoelectricconversion elements PD1 and PD2 within one pixel PX1 or PX2 areadjacently arranged in the first direction Dr1 and the second isolator124 positioned between the first and second photoelectric conversionelements PD1 and PD2 is approximately extended in the second directionDr2, a position of the second isolator 124 within the pixel PX1 or PX2in the first direction Dr1 may be changed according to a position of thecorresponding pixel PX1 or PX2 in the pixel array unit 300.

Referring to FIGS. 20 and 21, when a pixel approximately positioned on acenter vertical line of the pixel array unit 300 is referred to as afirst pixel PX1 and a pixel Px positioned at a border of the same row asthat of the first pixel PX1 is referred to as a second pixel PX2, thesecond isolator 124 included in the first pixel PX1 may be approximatelypositioned at a center of the first pixel PX1 on a plane, and the secondisolator 124 included in the second pixel PX2 may deviate from thecenter of the second pixel PX2 and slantly (and/or diagonally)positioned toward a border facing the first pixel PX1. In the mostpixels Px, sizes of the first and second photoelectric conversionelements PD1 and PD2 may be approximately the same as each other.

A position of the second isolator 124 within each pixel PX1 or PX2 inthe first direction Dr1 with respect to a center of each of the pixelsPX1 and PX2 may be gradually changed from the vertical center line ofthe pixel array unit 300 to left and right borders, and a direction, inwhich the second isolator 124 gradually moves, may be a directionheading the vertical center line of the pixel array unit 300.

Referring to FIG. 21, positions of the color filter 130 and themicro-lens ML positioned on the semiconductor substrate 120 with respectto the center of each of the pixels PX1 and PX2 in the first directionDr1 may also be changed according to a position of the pixel, like thesecond isolator 124. That is, the centers of the color filter 130 andthe micro-lens ML positioned in the first pixel PX1 may approximatelycorrespond to the center of the first pixel PX1, and the centers of thecolor filter 130 and the micro-lens ML included in the second pixel PX2may deviate from the center of the second pixel PX2 and be slantly(and/or diagonally) positioned toward the first pixel PX1.

The positions of the color filter 130 and the micro-lens ML with respectto a center of each pixel in the first direction Dr1 may be graduallychanged from the vertical center line of the pixel array unit 300 toleft and right boarders, and the direction, in which the color filter130 and the micro-lens ML gradually move, may be a direction heading thevertical center line of the pixel array unit 300. Further, the quantityof position change of the color filter 130 in the first direction Dr1may be larger than the quantity of position change of the micro-lens MLin the first direction Dr1. Accordingly, as illustrated in FIG. 21, themicro-lens ML positioned in the second pixel PX2 has been further movedthan the color filter 130 under the micro-lens ML.

When the second isolators 124, the color filters 130, and themicro-lenses ML of all of the pixels included in the pixel array unit300 have the same positions within the corresponding pixel, a differencein the quantity of received light of each of the first and secondphotoelectric conversion elements PD1 and PD2 included in the pixelpositioned at the center of the pixel array unit 300 is small, but theremay be a difference in the quantity of received light of each of thefirst and second photoelectric conversion elements PD1 and PD2 includedin the pixel positioned at the border of the pixel array unit 300.

However, according to some example embodiments, the positions of thesecond isolator 124, the color filter 130, and the micro-lens ML withrespect to the corresponding pixel PX1 or PX2 are gradually changedaccording to the position of the pixel PX1 or PX2, so that asillustrated in FIG. 21, even when light is slantly (and/or diagonally)incident from the side, it is possible to reduce and/or minimize adifference in the quantity of light incident into the first and secondphotoelectric conversion elements PD1 and PD2. Accordingly, it ispossible to decrease a defect of the image, the phase difference, andthe autofocusing information obtained from the autofocusing pixel PF orthe normal pixel PN positioned around the pixel array unit 300.

In the cross-sectional structure illustrated in FIG. 21, the secondisolator 124 may be extended to an inner side of the first or secondphotoelectric conversion elements PD1 or PD2, but is not limitedthereto, and a lower surface of the second isolator 124 may also be (ormay alternatively be) spaced apart from an upper surface of the first orsecond photoelectric conversion element PD1 or PD2.

Next, a pixel array unit 300 included in an image sensor according tosome example embodiments will be described with reference to FIGS. 22and 23 together with FIGS. 20 and 21.

Referring to FIGS. 22 and 23, the pixel array unit 300 according to someexample embodiments may include a semiconductor substrate 120C includingfirst and second photoelectric conversion elements PD1 and PD2, a wiringlayer 110, a color filter 130, a micro-lens ML, an insulating layer 140,and the like, and the semiconductor substrate 120C may include a firstisolator 122A and a second isolator 124A. In some example embodiments,the semiconductor substrate 120C, the wiring layer 110, the color filter130, the micro-lens ML, and the insulating layer 140 are mostly the sameas the corresponding configurations described above, but the pixel arrayunit 300 may further include a third isolator 125 positioned within eachof the pixels PX3 and PX4.

The structures of the first isolator 122A and the second isolator 124Amay be mostly the same as those described above illustrated in FIGS. 20and 21.

The third isolator 125 may be positioned within the semiconductorsubstrate 120C and may be approximately extended in the first directionDr1 on a plane structure, but is not limited thereto. The third isolator125 may cross the first and second photoelectric conversion elements PD1and PD2 in the first direction Dr1. The third isolator 125 may also be(or may alternatively be) connected with or spaced apart from the firstisolator 122A.

In the cross-sectional structure illustrated in FIG. 23, the thirdisolator 125 may be extended to an inner side of the first or secondphotoelectric conversion elements PD1 or PD2, but is not limitedthereto, and a lower surface of the third isolator 125 may also be (ormay alternatively be) spaced apart from an upper surface of the first orsecond photoelectric conversion elements PD1 or PD2. A depth of thethird isolator 125 from the first surface BS of the semiconductorsubstrate 120C may be approximately the same as a depth of the secondisolator 124A.

A position of the third isolator 125 according to some exampleembodiments with respect to a center of the pixel PX3 or PX4 may bechanged according to the position of the pixel PX3 or PX4 like the samescheme as that of the second isolator 124A described above, but amovement direction of the third isolator 125 may be different.

When a pixel approximately positioned on a center horizontal line of thepixel array unit 300 is referred to as the third pixel PX3 and a pixelpositioned in the same column as that of the third pixel PX andpositioned at a border of the pixel array unit 300 is referred to as thefourth pixel PX4, the third isolator 125 included in the third pixel PX3may be approximately positioned at a center of the third pixel PX3, andthe third isolator 125 included in the fourth pixel PX4 may deviate fromthe center of the fourth pixel PX4 and be slantly (and/or diagonally)positioned toward the border facing the third pixel PX3 in a planestructure. A position of the third isolator 125 within each of thepixels PX3 and PX4 in the second direction Dr2 may be gradually changedfrom the horizontal center line of the pixel array unit 300 to upper andlower borders of the pixel array unit 300, and the gradual movementdirection of the third isolator 125 may be a direction facing thehorizontal center line of the pixel array unit 300.

Referring to FIG. 23, the color filter 130 and the micro-lens MLpositioned on the semiconductor substrate 120C may have the sameposition change as that of the example in FIGS. 20 and 21, and thepositions of the color filter 130 and the micro-lens ML in the seconddirection Dr2 may also be (or may alternatively be) changed according tothe position of the pixel like the third isolator 125. That is, thecenters of the color filter 130 and the micro-lens ML positioned so asto correspond to the third pixel PX3 may approximately correspond to thecenter of the third pixel PX3, and the centers of the color filter 130and the micro-lens ML included in the fourth pixel PX4 may deviate fromthe center of the fourth pixel PX4 and slantly (and/or diagonally)positioned toward the third pixel PX3.

The positions of the color filter 130 and the micro-lens ML with respectto a center of each pixel in the second direction Dr3 may be graduallychanged from the horizontal center line of the pixel array unit 300 toupper and lower boarders of the pixel array unit 300, and the direction,in which the color filter 130 and the micro-lens ML gradually move, maybe a direction heating the horizontal center line of the pixel arrayunit 300. Further, the quantity of position change of the color filter130 in the second direction Dr2 may be larger than the quantity ofposition change of the micro-lens ML in the second direction Dr2.Accordingly, as illustrated in FIG. 23, the micro-lens ML positioned inthe fourth pixel PX4 has been further moved than the color filter 130under the micro-lens ML.

Last, an electronic device including an image sensor according to someexample embodiments will be described with reference to FIG. 24.

Referring to FIG. 24, an electronic device 1000 according to someexample embodiments may include an image sensor 1 according to someexample embodiments of the present disclosure, an optical system 2including at least one photographing lens, and the like.

In some example embodiments, the image sensor 1 may further include asignal processing unit 3. The signal processing unit 3 may include thefirst driver 400, the second driver 500, and the timing controller 600,which are described above. The signal processing unit 3 may receivefirst and second sub pixel signals from a pixel array unit 300, anddetect a phase difference for an object. The signal processing unit 3may determine autofocusing information, such as a distance from thepixel array unit 300 to the object, whether the object is in focus, andthe degree by which the object is out of focus, by using the detectedphase difference. According to a result of the determination, the signalprocessing unit 3 may transmit a control signal to the optical system 2and control a focus of the optical system 2. The focus of the opticalsystem 2 may be adjusted by controlling a distance between the lens andthe pixel array unit 300, and the like. After the adjustment of thefocus, the image sensor 1 may detect an image and obtain image datahaving high resolution image quality. The electronic device 1000 may bea digital camera, a camcorder, a robot, and the like.

While some example embodiments have been particularly shown anddescribed, it will be understood by one of ordinary skill in the artthat variations in form and detail may be made therein without departingfrom the spirit and scope of the claims.

1.-20. (canceled)
 21. A method of driving an image sensor, the imagesensor including a plurality of pixels, the plurality of pixelsincluding at least one autofocusing pixel and at least one normal pixel,each of the plurality of pixels including a plurality of photoelectricconversion elements, the method comprising: reading out autofocusingpixel signals, which are photoelectrically converted by the plurality ofphotoelectric conversion elements included in one of the at least oneautofocusing pixel, respectively, at different timings; and reading outnormal pixel signals, which are photoelectrically converted by theplurality of photoelectric conversion elements included one of the atleast one normal pixels, respectively, simultaneously.
 22. The method ofclaim 21, wherein the reading out the autofocusing pixel signalsincludes: applying a first transmission signal activated at a firsttiming to the at least one autofocusing pixel; and applying a secondtransmission signal activated at a second timing different from thefirst timing to the at least one autofocusing pixel.
 23. The method ofclaim 22, wherein the reading out the autofocusing pixel signalsincludes applying the first transmission signal activated at the secondtiming to the at least one autofocusing pixel.
 24. The method of claim22, wherein the reading out the normal pixel signals includes applying athird transmission signal activated at a third timing after the secondtiming to the at least one normal pixel.
 25. The method of claim 22,wherein the reading out the autofocusing pixel signals includes:obtaining a first sub pixel signal and a second sub pixel signal; anddetecting a phase difference between light incident to a first sub areaand a second sub area of the at least one autofocusing pixel, based onthe first sub pixel signal and the second sub pixel signal, wherein thefirst sub area includes a first photoelectric conversion element amongthe plurality of photoelectric conversion elements of the at least oneautofocusing pixel, and the second sub area includes a secondphotoelectric conversion element among the plurality of photoelectricconversion elements of the at least one autofocusing pixel.
 26. Themethod of claim 25, wherein the obtaining the first sub pixel signal andthe second sub pixel signal includes: reading out the first sub pixelsignal between the first timing and the second timing; and reading outthe second sub pixel signal after the second timing.
 27. The method ofclaim 26, wherein the second transmission signal is deactivated at thefirst timing, and the first transmission signal is deactivated at thesecond timing.
 28. The method of claim 25, wherein the obtaining thefirst sub pixel signal and the second sub pixel signal includes: readingout the first sub pixel signal between the first timing and the secondtiming; reading out a sum of the first sub pixel signal and the secondsub pixel signal after the second timing; and calculating a subtractionbetween the sum and the first sub pixel signal to obtain the second subpixel signal.
 29. The method of claim 28, wherein the secondtransmission signal is deactivated at the first timing, and the firsttransmission signal is activated at the second timing.
 30. The method ofclaim 25, wherein: the first sub pixel signal corresponds tophotocharges generated by the first photoelectric conversion element,and the second sub pixel signal corresponds to photocharges generated bythe second photoelectric conversion element.
 31. The method of claim 25,further comprising: determining autofocusing information correspondingto an external object based on the phase difference.
 32. A method ofdriving an image sensor, the image sensor including a plurality ofpixels, the plurality of pixels including at least one autofocusingpixel and at least one normal pixel, each of the plurality of pixelsincluding a plurality of photoelectric conversion elements, the methodcomprising: applying a first transmission signal activated at a firsttiming to the at least one autofocusing pixel to obtain a first subpixel signal; applying a second transmission signal activated at asecond timing different from the first timing to the at least oneautofocusing pixel to obtain a second sub pixel signal; applying a thirdtransmission signal activated at a third timing different from thesecond timing to the at least one normal pixel to obtain a pixel signal;obtaining image data corresponding to at least one autofocusing pixel byusing a sum of the first sub pixel signal and the second sub pixelsignal; and obtaining image data corresponding to at least one normalpixel by using the pixel signal.
 33. The method of claim 32, wherein thesecond timing is later than the first timing and earlier than the thirdtiming.
 34. The method of claim 32, wherein the at least oneautofocusing pixel includes a first sub area and a second sub area, thefirst sub pixel signal corresponds to photocharges of the first subarea, and the second sub pixel signal corresponds to photocharges of thesecond sub area.
 35. The method of claim 34, further comprising:detecting a phase difference between light incident to the first subarea and a second sub area of the at least one autofocusing pixel, basedon the first sub pixel signal and the second sub pixel signal; anddetermining autofocusing information corresponding to an external objectbased on the phase difference.
 36. The method of claim 34, wherein: theat least one autofocusing pixel includes a floating diffusion node; andin one of the at least one autofocusing pixel, the photocharges of thefirst sub area are transmitted to the floating diffusion node inresponse to activation of the first transmission signal and thephotocharges of the second sub area are transmitted to the floatingdiffusion node in response to activation of the second transmissionsignal.
 37. The method of claim 36, wherein: the floating diffusion nodestores the photocharges of the first sub area, between the first timingand the second timing; and the floating diffusion node stores thephotocharges of the first sub area and the photocharges of the secondsub area, after the second timing.
 38. The method of claim 32, whereinthe applying the first transmission signal includes applying the firsttransmission signal to a first transmission transistor of the at leastone autofocusing pixel; the applying the second transmission signalincludes applying the second transmission signal to a secondtransmission transistor of the at least one autofocusing pixel, thesecond transmission transistor being different from the firsttransmission transistor; and the applying the third transmission signalincludes applying the third transmission signal to transmissiontransistors of the at least one normal pixel, simultaneously.
 39. Themethod of claim 32, wherein: the third timing is the same as the firsttiming.
 40. The method of claim 39, wherein: the third transmissionsignal is the same as the first transmission signal.